Norwegians may be thankful that a researcher at a museum was less than inventive in choosing a password to protect its electronic library.

Reidar Djupedal took to the grave the password he had chosen for the electronic archive of books and documents.

But it only took hackers five hours to crack the code and unlock the valuable archive.

A 25-year-old Swede is credited as having discovered that the password was ladepujd, the researcher's name spelt backwards.

"It sounds simple now that we have the answer, but the database was created in an old program that few have now, and the public institutions we asked for help didn't manage to crack the code," Ottar Grepstad, director of the Ivar Aasen Centre of Language and Culture, told the Aftenposten newspaper.

"It is interesting that this case has sparked a serious debate among computer experts about how one should take care of an important password," he said.

Simply names

The internet appeal for help by the Aasen Institute provoked a flood of e-mail suggestions and discussions on the web.

Within hours, it became clear that the answer was the researcher's name backwards. But the institute waited over the weekend to see if that information was enough to allow full access to the valuable index.

In fact, this password was only the first step. Accessing the database required another password but this one was even simpler - the researcher's first name.

Experts recommend you should use a full sentence as a password, and add some symbols and numbers at the end of it.

Alternatively, you should pick a cycle of words that mean something to you from your past and change one of the letters to a number, like an E to a 3.

The database compiled by Reidar Djupedal indexed over 11,000 titles. It would have taken the institute about four years of work to recreate the catalogue had they failed to find the password.

The Aasen centre researches Norway's second language Nynorsk, compiled by linguist Ivar Aasen from the country's local oral dialects.